Method for incorporating oil-insoluble, solid addition agents in mineral oils



United Statcs Patent ll/IETHOD FORLINCORPORATING OIL-INSOLUBLE, SOLIDADDITION AGENTS IN MINERAL OILS Edward:A..0berright, Woodbury, N. J.,assignor to SoggmygMobil-Oil Company, Inc., a corporation of New or i NoDrawing. Application June 8, 1953, Serial No; 360,349

4 Claims. (Cl. 252'-25) This invention relates generally to improvedlubricating oil compositions. More particularly, it relates to a novelmeans for the incorporation of certain improving agents into lubricatingoils and to a novel form of such addition agents.

As is wellknown, it is the practice in the art today to add.tolubricating. oils minor amounts of chemical agents to improvevariouslubricating characteristics of such-oils. A greatnumber and varietyofsuch improving agents are known. The present invention is directedprimarily to solid lubricating oiladdition agents of the inorganic typewhich are insoluble in lubricating oils. These include particularly theoxides, hydroxides and carbonates of the alkali and alkaline earthmetals, such as potassium hydroxide, sodium hydroxide, calcium oxide,calcium hydroxide, calcium carbonate, barium hydroxide, strontiumhydroxide, zinc oxide, etc. However, the principle of the invention isapplicable to solid inorganic type, oil-insoluble addition agents ingeneral. Although these additives. are insoluble in engine lubricatingoils, they may be dispersed therein and, when so dispersed, they providehighly desirable improvements in the oil. Thus, they inhibit increaseofacidify of the oil'in use so that corrosion of the. engine parts withwhich the oil comes in contact is substantially reduced. They alsoimprove the detergent character. of

the oil; so that the deposition of sludge on the engineparts iseffectively reduced. Due to the high efiectiveness thus exhibited bythese additives, as Well as their relatively low cost andavailability,their use in engine oils is highly desirable. However, the fact thatthey are insoluble in the oil constitutes a serious drawback to theirusefrom the marketing angle. Thus, the oil containing the dispersed'additivehas a cloudy appearance. Also, on long standing the additivetends to settle out of the oil. Actually, the cloudy appearance of theoil does not detract fromitsquality, nor does the settlingout'of'theadditive affect 'its etfi'ciencysince, in the engine, theadditive is re-' dispersed in the oil whenever the engine is startedup.

However, the. cloudy appearance of the oil creates a doubt in thecustomers mind as to its quality. Away of "utiliz ing thednorganicaddition agents which would'solve the" problemiof customerresistancewas,therefore, sought.

A possible solution which suggested itself was that these additivescould be marketed separately for addition to the oil at the: pointofuse, i. e., in the engine, rather than at the point of manufacture. Inthis-way, the beneficial use f..these additives would be attaineclwhilethe marketing problem would'be eliminated. Such a .manner: of use,however, posed the further problem of-supplying-theadditives in, a formwhich would be convenient forrhandling andwhich at the same timewouldbeefiiciently dispersible in.the oil. To give a ready, dispersiontil]. the oil, these solid, inorganic additives must be added to the oil.in finely divided form; i. e., the particle size should be no greaterthan about 45 microns; Distributionlof the additives in this form,however, would not befeasibleior several reasons. In-the-first-place;itwouldbe'costly, since separate, weighed portions, ordosages, of the additives would have ICC 2, to be prepared and. packagedin some manner for such distribution. Also, thisform of the additivewould be unattractive from the marketing angle. The object ofthis-invention is, therefore, to provide a means for. the utilization ofthese additives which is convenient and practicable as well asattractive from the marketing standpoint. A further object is theprovisionof a novel form of these addition agents for addition tolubricating oils.at the point of use. Other and further objects of theinvention will become apparent from the followingdescription thereof.

The present invention provides a mostconvenient and practicable form ofthe solid,. inorganic, oil-insoluble addition agents. This novel'form ofadditive comprises solid, composite pellets of the finely divided.additive and' a wax binding material. In this form the additives may beadded to the lubricatingoilat the point of use, such as in the crankcaseof an engine,.and provide a ready dispersionof the, additive in the oil;

In accordance with the invention, the additive is.prepared as follows:The additiveis ground, ifnecessary, and passedthrough a 325' mesl1screentoiprovide a particle size not greater than approximately45microns. A wax, such as a paraflin wax, is-heatedabove its melting pointand the comminuted additive is mixed with the liquid wax, with stirring,to provide a homogeneous dispersion of theadditive: in the wax;This-mixture iscthen formed into pellets in anysuitablewmanner, such asby pouring-it into molds-andallowing it to cool .and solidify.

The;unique.advantage.. of the pellets of the invention .is that'theadditive is maintaineditherein.in a finely divided; readily dispersible,state. Upon addition-of" the pellets" to the. oil, the. wax-1 component.dissolves. and the; finelyv divided: additive is. simultaneouslydispersed. in. the Oilxi. Compacted pellets of the addition agents perse, on:the-: other hand, will not'give. a-satisfactory dispersionofr'the additive inthe oil, evenwhenzthe. engine is operatedfori aconsiderable period.

The wax used in forming the pellets of therinve-ntion' may be anyoil-soluble wax, or wax-like material, which, is solidat temperatures upto at least 10O 125 F. Suitable Waxes are, for example, parafi'n Wax,japan wax, carnuba wax, beeswax, spermaceti, 1 octadecanol, etc;,paraffin' Wax' being particularly preferred.

The following examples show the utility oft'he invention from thestandpoint of providing the effective disper. sion of solid additionagent upon addition to the lubricat-' ing oil in an internalcombustiorrengine.

EXAMPLEI Zinc. oxideewax pellets Zinc" oxide was prepared in Y the formof zinc oxide waxpellets -as'-follows. Powdered zinc oxide was passedthrough a32 5 mesh screento provide aparticle sizeof' not greaterthanASm-icmnsand then mixed with' hot, liquid "paraffin wax (meltingpoint 1204 25 F.) and the: heated mixturesfirred thoroughly. The mixturewas them poured into a=series-of"molds' andall'owed tocool and solidify;The'pell'ets thus ob'taincd' contained 40% -by' Weightof zinc oxide:

The pellets were: tested in i the" Lausorn Oxidation- S't-a bility TestOS'--2: This-"test-involves thie operation-of" the single cylinder," 4cycle li'q-uid cooledengine for hours under the following conditions:

One-half "throttle 13."01 air-fuel' ratio Oil addd "every;20 hours i Thetest determines oil deterioration as primarily indicated by corrosion ofthe copper-lead bearing and secondarily by engine cleanliness. Thecopper-lead bearing of the engine is accurately weighed before and afterthe test run and the loss in weight thereof recorded. The engine whichis clean at the start of the test is inspected after the test run forcleanliness of the rings, lands, ring grooves and piston skirt.Cleanliness ratings are made, based on a scale of from 100 to zero, arating of 100 signifying a perfectly clean engine and a rating of zerorepresenting the worst possible deposit condition.

To test the pellets, a sufficient number thereof were added to the baseoil, an S. A. E. 20 grade Pennsylvania motor oil, in the crankcase ofthe engine, via the oil addition tube, to give a 0.5% weightconcentration of zinc oxide in the oil. With each addition of make-upoil, sufficient pellets were added to maintain this original additiveconcentration. The fuel used was a blended gasoline comprising 40%thermal plus 30% catalytically cracked plus 30% straight run plus 2.5cc. of TEL. A control test was also conducted on the base oil alone.

The test with the base oil alone showed a bearing weight loss of 394milligrams per half-bearing and an engine cleanliness rating of 77,while the test utilizing the zinc oxide-wax pellets showed a bearingweight loss of 76 milligrams per one-half bearing and an enginecleanliness rating of 82.

EXAMPLE II Calcium hydroxide-wax pellets A high grade of calciumhydroxide, known as Greasemakers Lime, was ground and passed through a325- mesh screen and stirred into hot, liquid scale wax (melting point125-127 F.). The stirring was continued for /2 hour after the additionof the lime to insure a homogeneous mixture. The mixture was then pouredinto molds and allowed to cool and solidifidy. The pellets thus obtainedcontained 31% by weight of calcium hydroxide.

The pellets were tested in the Lauson D-4A Detergency Test. This testinvolves the operation of the single cylinder, 4-cycle, liquid cooledengine for 100 hours under the following conditions:

Oil temperature F 225 Jacket temperature F 275 Speed R. P. M 1825 Brakeload H. P 1.6

One-half throttle 13-1 air-fuel ratio Oil added every 20 hours This testdetermines the efiectiveness of the lubricating oil in preventingfouling as measured by the cleanliness of the rings, lands, ring groovesand piston skirts. Engine cleanliness ratings are assigned on a scale of100 to zero in the same manner as for the Lauson OS-2 Test.

To test the calcium hydroxide-wax pellets, a suflieient number of thepellets were added to the base oil in the crankcase of the engine, viathe oil-addition tube, to provide 1% by Weight of calcium hydroxide inthe engine oil. The base oil used was an S. A. E. 20 grade Pennsylvaniamotor oil. With each addition of make-up oil during the test run,sufiicient pellets were added to maintain this original additiveconcentration. The fuel used was the same as defined in Example I. Atest was conducted on the base oil also as a control.

The test conducted on the oil alone gave an engine cleanliness rating of65, while the test using the calcium hydroxide-wax pellets gave a ratingof 80.

The size of the pellets and the proportion of additive therein can, ofcourse, be controlled. The pellets may contain as little as about and upto 90% of the additive. Generally, it is preferred to so design thepellets that one pellet will supply the required improving amount ofadditive for a specified quantity of oil. The

number of pellets to be added in any case is then determined by thevolume of oil to be treated. For use in automobile engines the pelletswill be of relatively small size since the amount of additive requiredis ordinarily small, i. e., from about 0.1% to about 10% by weight; and,a pellet comprised, for example, of 50% addition agent and 50% bindingmaterial and weighing 16 grams will supply 1% of additive to one quartof oil.

Although, as heretofore indicated, the principle of this invention isprimarily applicable to the incorporation in oil of the solid,oil-insoluble, inorganic-type addition agents, it will be appreciatedthat it may be advanta geously applied to any solid-type additive,including the elemental metals and solid, oil-soluble, organic additionagents, since it provides a convenient means of adding controlledamounts of such additives to the oil at the point of use, whereby theoil is fortified to meet special operational conditions, or refortifiedas the addition agents originally present therein become depleted byuse. The invention may also find useful application in the addition ofadditives to hydrocarbon fractions, other than lubricating oils, such asfuel oils, gasolines, etc.

Having now fully described the invention, what is claimed as new andpatentable is:

l. A method for incorporating an oil-insoluble, solid, addition agentinto a mineral oil fraction, which comprises (1) comminuting theaddition agent to an average particle size no greater than about 45microns, (2) forming a compacted pellet comprising from about 10% toabout by weight, of the comminuted addition agent and from about 90% toabout 10%, by weight, of a wax binder and (3) adding the said pellet tothe mineral oil fraction.

2. A method for incorporating a solid, inorganic basic compound,selected from the group consisting of the metal oxides and hydroxides ofthe metals of Group II of Mendeleeffs Periodic Table of the Elements,into a mineral lubricating oil which comprises (1) comminuting the saidcompound to an average particle size no greater than about 45 microns,(2) forming a compacted pellet comprising from about 10% to about 90%,by weight, of the comminuted solid basic compound and from about 90% toabout 10%, by weight, of a wax binder and (3) adding the said pellet tothe oil.

3. A method for incorporating solid zinc oxide into a minerallubricating oil which comprises 1) comminuting the zinc oxide to anaverage particle size no greater than about 45 microns, (2) forming acompacted pellet comprising from about 10% to about 90%, by weight, ofthe comminuted zinc oxide and from about 90% to about 10%, by weight, ofa wax binder and (3) adding the said pellet to the oil.

4. A method for incorporating solid calcium hydroxide into a minerallubricating oil which comprises (1) comminuting the calcium hydroxide toan average particle size no greater than about 45 microns, (2) forming acompacted pellet comprising from about 10% to about 90%, by weight, ofthe comminuted calcium hydroxide and from about 90% to about 10%, byweight, of a wax binder and (3) adding the said pellet to the oil.

References Cited in the file of this patent UNITED STATES PATENTS1,699,274 Bohart Jan. 15, 1928 2,079,051 Sullivan May 4, 1937 2,110,503Duckham Mar. 8, 1938 2,292,047 Calhoun Aug. 4, 1942 2,485,861 Campbellet al Oct. 25, 1949 2,671,758 Vinograd et a1 Mar. 9, 1954 2,676,925Lindstrom et a1 Apr. 27, 1954 FOREIGN PATENTS 360,121 Great Britain Nov.5, 1931

1. A METHOD FOR INCORPORATING OIL-INSOLUBLE, SOLID, ADDITION AGENT INTOA MINERAL OIL FRACTION, WHICH COMPRISES (1) COMMINUTING THE ADDITIONAGENT TO AN AVERAGE PARTICLE SIZE NO GREATER THAN ABOUT 45 MICRONS, (2)FORMING A COMPACTED PELLET COMPRISING FROM ABOUT 10% TO ABOUT 90%, BYWEIGHT, OF THE COMMINUTED ADDITION AGENT AND FROM ABOUT 90% TO ABOUT10%, BY WEIGHT, OF A WAX BINDER AND (3) ADDING THE SAID PELLET TO THEMINERAL OIL FRACTION.